1. Field of the Invention
The present invention relates to the field of ankle and foot orthosis and more particularly to rigid ankle and foot orthosis used in athletic and medical applications for individuals who have injured their ankle or have an unstable ankle joint.
2. Brief Description of the Prior Art
Ankle orthoses and ankle and foot orthoses have become a popular form of treatment for controlling lateral ankle motion in the injured or unstable ankle. Lateral ankle injuries account for the majority of ankle injuries. These injured ankles have a high probability of suffering recurring sprains and increased joint laxity. The ankle joint is an articulation involving the tibia and fibular with the talus. The talus also forms a major articulation with the calcaneus (sub-talor joint). As the ankle joint is very intimately connected to the sub-talor joint in the foot, an ankle and foot orthosis must ideally control lateral ankle motion (inversion) and sub-talor joint motion (supination). In addition, for an orthoses to be considered functional, it must minimally restrict all other motions including plantarflexion/dorsiflexion at the ankle (up/down motion of the foot) and natural pronation of the foot (inward rotation with flattening of the arch). An orthosis that can achieve all these criteria can represent a significant improvement in function.
Rigid ankle bracing was popularized by the xe2x80x9caircastxe2x80x9d stirrup ankle brace described by Johnson, Jr., U.S. Pat. No. 4,280,489. This discloses an orthosis consisting of two outer injection molded plastic shells (commonly referred to as xe2x80x9cstirrupsxe2x80x9d) with two inner inflatable air bags/bladders. The shells lie against the medial side and lateral side of the heel, ankle and lower leg and are connected above the ankle by two Velcro(copyright) straps and are connected distally by a strap under the heel.
Prior Patents to Grim, (U.S. Pat. Nos. 4,844,094; 5,092,319; 5,348,530; 5,445,602); Brewer, U.S. Pat. No. 4,966,134; Hess, U.S. Pat. No. 5,038,762; Johnson, Jr., (U.S. Pat. Nos. 5,125,400; 5,389,065); Makinen, U.S. Pat. No. 5,199,941; Montag, U.S. Pat. No. 5,472,411; Morris, U.S. Pat. No. 5,501,659; Iglasias, (U.S. Pat. Nos. 5,716,335; 5,951,504) all disclose similar stirrup arrangements with differing padding and/or strapping mechanisms and/or adjustments to the shapes of the shells.
Alternatively, Peters, U.S. Pat. No. 4,510,927 disclosed a variation to the traditional stirrup design by utilizing the addition of a medial and a lateral hinge placed at the level of the anatomical ankle joint axis. Peters, (U.S. Pat. Nos. 5,031,607; 5,366,439, 5,836,903; 6,053,884); Swearington, U.S. Pat. No. 5,056,509, Prock, U.S. Pat. No. 5,069,202; Miklaus, U.S. Pat. No. 5,209,072; Harris, U.S. Pat. No. 5,242,379; Wehr, U.S. Pat. No. 5,503,622; McDavid, U.S. Pat. No. 5,797,865; Quinn, U.S. Pat. No. 5,971,946 all disclose variations to the hinged stirrup design, varying essentially by any combination of changes to the shape/position of the shells, strapping mechanism and/or padding mechanism.
Others have disclosed single hinged devices. Nelson, U.S. Pat. No. 4,719,926 and Wilkerson, U.S. Pat. No. 5,445,603 disclose lateral hinged stirrup orthoses. Wilkerson, U.S. Pat. No. 5,902,259 also discloses a medial hinged stirrup device. This device has a medial hinge and a lateral supporting structure with a lateral malleolar aperture. However, this device fails to extend over the latero-superior aspect of the talar head and therefore lacks supination control. Also, the device extends much higher on the lateral aspect of the leg applying pressure to the fibular shaft and neck and does not rigidly connect the footplate to the lateral support structure.
All of the prior art orthoses are flawed by any combination of the following defects: loss of intimate contact on the medial calcaneus; loss of intimate contact on/around the fibular malleolus; no force application over the latero-superior aspect of the talar head; loss of rigidity in the medial lever; lack of a distal counteractive force on the forefoot needed to control rotation of the talus; restriction of dorsiflexion and/or plantarflexion; restriction of functional pronation.
Accordingly, the above problems and difficulties are avoided by the rigid ankle and foot orthosis presented herein as the inventive device or brace applies forces to specific areas of the ankle and foot to effectively limit lateral motion of the fibular malleolus (inversion) and lateral/superior rotation of the talus (supination) while avoiding any unnecessary additional contact and allowing all other motions of the foot and ankle to be unrestricted.
In one form of the invention, the orthosis or brace includes two contoured semi-rigid plastic shells. A medial/plantar/lateral shell extends from the medial malleolus down under the foot and then up over the fibular malleolus and the latero-superior aspect of the talus. An aperture in the shell lies in the area of the fibular malleolus. The lateral section and aperture are covered interiorly by a cushioning pad of a non-elastic nature to cushion the malleolus and prevent lateral displacement. Superiorly, the lateral section forms a bridge between the posterior and anterior margins to avoid pressure on the fibular shaft and neck. A stirrup shaped medial shell lies against the medial aspect of the cibia and connects to the medial portion of the medial/plantar/lateral shell. Interiorly disposed of this shell lies a cushioning pad. A screw or pin connects the two plastic shells forming a pivot hinge and is placed at the position of the anatomical ankle axis. An additional pivot or screw connects the two shells and slides through an arcuate slot in the medial shell. Three straps connectably fasten the orthosis to the ankle and foot.
Therefore, a primary object of the present invention is to provide an ankle and foot orthosis that effectively limits lateral fibular malleolar displacement, i.e. inversion. Another object of the present invention is to provide an ankle and foot orthosis that effectively limits latero-superior rotation of the talus, i.e. supination. A still further object of the present invention is to provide an ankle or foot orthosis that has minimal resistance to all other motions, namely plantarflexion, dorsiflexion and pronation.
An even further object of the present invention is to provide an ankle and foot brace that has minimal contact on the leg, ankle and foot by avoiding unnecessary contact thereby keeping the bulk of the orthosis to a minimum and allowing easy fitting into a users shoe.
A further object of the present invention is to provide a comfortable, inexpensive ankle orthosis that can be economically manufactured.